The fundamental frequency of an electric motor generally increases with a greater pole count of the electric motor. Real hardware delays, which may be ignored in lower fundamental frequency applications, become significant in electric motors having a greater pole count, and these delays may undesirably affect control performance absent compensation. While the fundamental frequency is generally increased for these electric motors, the switching frequency, as well as sampling frequency, typically remains substantially constant. For example, processor throughput and switching loss limitations predominantly affect the switching and sampling frequencies.
One indication of motor control capability is a pulse ratio, which may be determined from a ratio of the switching frequency to the fundamental frequency for the electric motor. The electric motor drive system is generally designed with a maximum possible pulse ratio. In electric motors with a greater pole count, the pulse ratio is typically reduced and can interfere with motor control and increase sensitivity to delays.
Accordingly, it is desirable to provide a method and apparatus for electric motor control that minimizes the effects of hardware delays. In addition, it is desirable to provide a method and apparatus for electric motor control that compensates for hardware delays. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.